Lithium Ion Button Cell Battery Single-Wall Casing Design
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Solution Overview
Problem
Rechargeable lithium-ion button cell batteries face challenges in achieving high volumetric energy density due to casing design and sealing methods, electrode arrangement, and limited cycle life, particularly in very small electronic devices like hearing aids where space is constrained and reliable, high-energy-density solutions are needed.
Innovation Solution
A sealed housing design with single-wall casings, spiral wound electrodes, and tapered width to optimize inner volume, along with reliable connection methods and anti-corrosion materials to extend cycle life, such as aluminum-coated current collectors and casings, is employed to enhance energy density and cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If folded double side walls are used for sealing, then reliable seal is achieved, but inner volume for active materials is reduced
Solution Approach 1:
The sealing structure is divided into two separate components: the outer casing with its own sealing rim and the inner casing with its own sealing rim. This segmentation eliminates the need for folded double side walls while maintaining reliable sealing through the combination of both casings' sealing features working together.
2Reliability
If thick casing design is used for sealing, then reliable seal is achieved, but significant volume is occupied
Solution Approach 1:
Instead of uniformly thick casing throughout, the design uses localized sealing rims at specific locations (outer casing rim and inner casing rim) where sealing is needed. The rest of the casing structure can be thinner, optimizing the balance between sealing reliability and volume consumption.
3Volume of stationary object
If spiral wound electrodes with vertical axis are used, then high inner volume utilization is achieved, but electrode connection to casings becomes complex
Solution Approach 1:
The electrode connection approach transitions from radial connection (complex for vertical spiral) to axial connection (simple for vertical spiral). The electrodes are connected to the casings at their axial ends, which simplifies the connection structure while maintaining high inner volume utilization achieved by the vertical spiral configuration.
4Use of energy by moving object
If aluminum current collectors are used, then high energy density is achieved, but corrosion resistance is reduced
Solution Approach 1:
The current collector system uses a composite structure: aluminum current collectors for high energy density combined with aluminum foil wrapping around the electrode assembly. This aluminum foil layer provides the necessary corrosion resistance protection while the aluminum current collectors maintain high electrical conductivity and energy density.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves a high volumetric energy density of 300 Wh/L with 400-1000 cycles to 80% remaining capacity, suitable for small devices like hearing aids, with improved reliability and assembly convenience.
Implementation Method 1
the outer casing opening rim is mechanically crimped to press the gasket firmly on the inner casing shoulder to complete the seal of the battery
Implementation Method 2
the anode and cathode electrodes are spiral wound with separator to be a round or oval roll
Implementation Method 3
aluminum-coated current collectors and casings
Implementation Method 4
anti-corrosion materials to extend cycle life
Implementation Method 5
The electrodes are tapered in width, to adapt the inner space height changes from the center of the casing to the shoulder rim
Data Source
AI summary
A rechargeable lithium ion button cell battery having a sealed housing comprises an inner casing and an outer casing, both casings have at least one flat area as top or bottom of the battery, and a round or oval side wall vertically formed to the flat area. Said side walls are single wall not folded double walls. An insulation gasket is positioned between said side walls, and the outer casing opening is mechanically crimped to complete the seal of the battery. Inside the sealed housing the anode & cathode electrodes are spiral wound with separator to be a round or oval roll. Said roll axis is vertical to the said flat areas of the casings. The two electrodes are tapered in width and comprise current collectors of metal foils coated with lithium-intercalating active materials, leaving small area of uncoated metal foils as welding tabs for connecting to the casings. The tabs are welded to the casings respectively, or for the tab of the electrode which connecting to outer casing, welded to an aluminum flake first and said flake is pressed on the outer casing by said gasket. Two insulation washers could be applied to inner side of the casings to prevent short circuit. Such battery has high energy density, low impedance, high reliability and long cycle life.